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ABSTRACIThe qualitative and quantitative aspects of elemental sulfur metabolization in wheat leaves and its effect upon photosynthetic metabolism were studied through the application of micronized sulfur upon the third leaf. Energy-dispersive x-ray analysis combined with scanning electron microscopy emphasized the existence of a sulfur peak associated with a strong potassium peak in the spectra of different tissue regions for treated leaves only, supplying an original evidence of sulfur uptake. Experiments with35S-labeled micronized sulfur showed that about 2% of the labeled S was absorbed and metabolized into cystine, methionine, glutathione, and sulfate. The close correlation between the excess of oxygen uptake and oxygen needs for sulfur oxidation in conjunction with the absence of hydrogen sulfide released by treated leaves support direct and fast oxidation of sulfur into sulfate according to a pathway still unclear but independent of photosynthetic CO2 metabolism in treated leaf. The mechanisms involved in the primary metabolism of element sulfur in wheat therefore appear to be different from those in fungi.Various transformation pathways for elemental S has been reported when this chemically stable element is in contact of living organisms. In bacteria, elemental S can be oxidized by several enzymic systems more or less described (3, 16) or reduced by a transmembrane system involving a Cyt C3 and an hydrogenase (4). In fungi, elemental S is reduced at the level of the respiratory chain (17), producing H2S and causing death. In the alga Chlorella, elemental S is metabolized as the reduced form (8); this pathway takes place also when the alga are fed with cysteine methyl-or ethyl-ester. In higher plants some experiments have provided evidence for its metbolization in leaves (R Pezet, P Zuccaroni, personal communication).These differences of behavior of living organisms toward elemental sulfur explained its use as fungicide for many centuries in viticulture, arboriculture and, more recently, in cereal crops.In the latter case foliar applied S has been claimed to increase grain yield, independently of fungicide effect. So, Scott et al. (14) have shown that foliar S treatment of barley increased the number of grains per ear, suggesting the possibility of advantageous influence on metabolism with higher plants.This study was aimed to investigate the fate of elemental S, when applied upon wheat leaves, and the eventual incidence of its metabolization upon the carbon metabolism of leaves. MATERIALS AND METHODSWheat (Triticum aestivum, cv Champlein) was planted in washed vermiculite with four seeds per 12 cm pot. The pots were irrigated with a nutrient solution complete or S042-free (1). Seedlings were grown with a 9 h light/ 15 h dark, a quantum flux of 200 ,mol m-2 s-', a relative humidity of 70%, and temperatures of 23°C in the light and 17°C in the dark, for 3 weeks. At the end of this period, the third leaf was grown up while the fourth one can be seen and was growing.Preparation of 35S Labeled Microballs (...

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Mineral nutrition of poppy (Paparer somniferum L.) was studied in its effects on morphine production. Hydroponic cultures were carried out with nutritive solutions percolating over sand. The anion NO3‐ is the most efficient form of nitrogen for the production of fresh matter, dry matter or total morphine; in the latter respect, it rates higher than the NH4NO3 form which, on the other hand, gives higher alkaloid contents, while both cation NH4+ and urea have depressive effects. Phosphates have apparently little effect on the growth of the poppy, but solutions enriched with assimilable phosphate do stimulate flower proliferation and fruit development, without increasing markedly the total morphine output. Mg2+ and Ca2+ are important factors; Mg deficiencies will bring about a marked elongation of stems and early flowering, without any notable decrease in morphine outputs; conversely, Ca deficiencies will cause a drop in alkaloid production, while more calcium in the solution will give stronger elongation, a larger number of capsules and a marked increase in the weight of dry matter and morphine outputs, without any marked change in content. Sodium will favour poppy development (flowers and capsules) and will increase both the content and output of morphine. Na+ should therefore be introduced whenever possible in the fertilizing of poppy crops.